FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Toyota/Corolla/E170 (2013-2019)/how to troubleshoot P0420 code on Toyota Corolla E170 (2013-2019)

how to troubleshoot P0420 code on Toyota Corolla E170 (2013-2019)

Toyota Corolla E170 (2013-2019)

Severity: highDifficulty: mediumError Code: P04203-5 hours
3 min read
554 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to troubleshoot and fix P0420 code in Toyota Corolla E170 (2013-2019). Step-by-step guide with diagnostic steps and repair instructions.

Error Code
P0420
Component
Exhaust System
Repair Time
3-5 hours

Safety Warnings

  • ⚠Disconnect the battery before working on electrical systems.
  • ⚠Allow the exhaust system to cool before handling components to avoid burns.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Poor engine performance or rough idling
  • •Failed emissions test
  • •Unusual exhaust odor (e.g., sulfur smell)

Diagnostic Steps

  1. 1Scan the vehicle's OBD-II system for error codes to confirm P0420 and check for additional codes.
  2. 2Inspect the exhaust system for any visible leaks, especially before and after the catalytic converter.
  3. 3Check the oxygen sensors' operation by monitoring their voltage output using a multimeter.
  4. 4Measure the temperature difference between the inlet and outlet of the catalytic converter with an infrared thermometer.
  5. 5Inspect the catalytic converter for physical damage or clogging.
  6. 6Verify fuel trims (short and long) using the OBD-II scanner to check for air-fuel mixture issues.

Solution

Solution

1. Preparation

  • Gather tools and parts needed for the repair.
  • Disconnect the battery to ensure safety during the repair process.
  • Tools Required: OBD-II scanner, multimeter, infrared thermometer, socket set, jack and jack stands.

2. Inspect and Replace Oxygen Sensors

  • Remove the Front Oxygen Sensor:
    • Locate the front (upstream) oxygen sensor.
    • Disconnect the electrical connector.
    • Use a wrench to unscrew and remove the sensor.
  • Install the New Oxygen Sensor:
    • Apply anti-seize compound to the threads of the new sensor.
    • Screw in the new sensor by hand and then tighten with a wrench to the manufacturer's specified torque (typically around 30 lb-ft).
    • Reconnect the electrical connector.

3. Inspect and Replace Catalytic Converter

  • Remove the Exhaust System Components:
    • Locate the bolts securing the catalytic converter to the exhaust system.
    • Use a socket set to remove these bolts and disconnect the exhaust sections if necessary.
  • Remove the Catalytic Converter:
    • Unclip any heat shields if present and carefully remove the catalytic converter from its mounting.
  • Install the New Catalytic Converter:
    • Position the new catalytic converter in place and secure it using new gaskets if required.
    • Reattach the exhaust sections and tighten all bolts to the specified torque.

4. Clear Codes and Test Drive

  • Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
  • Take the vehicle for a test drive to ensure that the check engine light does not reappear and that the engine operates smoothly.

Verification

After completing the repair, verify that the issue has been resolved:

  • Test the affected component to ensure it functions correctly
  • Check for any error codes or warning lights
  • Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • OBD-II scanner
  • Multimeter
  • Infrared thermometer
  • Socket set
  • Jack and jack stands

Parts Required

  • Front oxygen sensor (if faulty)
  • Catalytic converter (if faulty)

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

3-5 hours

Difficulty

medium

Severity

high

Tools

5 items

Parts

2 items

Related Faults

Discover similar issues

  1. How to fix loss of power Toyota Corolla

    Learn how to diagnose and repair loss of power in Toyota Corolla E170 models. Follow these steps to identify and fix issues affecting engine performan...

    Component:engine
    Symptoms
    • •Sluggish acceleration
    • •Difficulty maintaining highway speeds
    • +{count} more
  2. Check engine light on Toyota Corolla

    Learn how to diagnose and resolve check engine light issues on Toyota Corolla E170 (2013-2019) using OBD-II scanner and basic tools.

    Component:engine, emissions system
    Symptoms
    • •check engine light illuminated
    • •rough idle
    • +{count} more
  3. why is my Toyota Corolla E170 (2013-2019) steering wheel so hard to turn?

    Discover the causes and solutions for a hard-to-turn steering wheel in the 2013-2019 Toyota Corolla E170. Step-by-step diagnostic and repair guide.

    Component:Steering
    Symptoms
    • •Difficulty turning the steering wheel, especially at low speeds
    • •Squeaking or whining noise when turning the steering wheel
    • +{count} more
  4. why is my Toyota Corolla E170 (2013-2019) making a whining noise

    Learn to diagnose and fix whining noise in Toyota Corolla E170 (2013-2019). Step-by-step guide with symptoms, diagnostic steps, and repair instruction...

    Component:Steering
    Symptoms
    • •Whining noise when the engine is running
    • •Noise increases with acceleration
    • +{count} more
  5. Diagnose fuel injector clogged Toyota Corolla

    P0300-P0304

    Learn how to diagnose and repair clogged fuel injectors on a Toyota Corolla E170 (2013-2019) with this comprehensive guide. Includes symptoms, diagnos...

    Component:fuel injector
    Symptoms
    • •Rough Idle
    • •Engine Misfire
    • +{count} more
  6. How to fix alternator failure Toyota Corolla

    Learn how to diagnose and repair alternator failure in a Toyota Corolla E170 (2013-2019) with detailed steps and required tools.

    Component:alternator
    Symptoms
    • •Battery Warning Light
    • •Dimming Lights
    • +{count} more

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation